The present invention pertains to catalyst systems having improved resistance under a corrosive environment, and more particularly to catalyst systems including a metal support structure with an anti-corrosive coating.
In chemical industry reactors, metallic catalyst support structures are preferred over inorganic (e.g., ceramic) catalyst supports because they exhibit high intrinsic thermal conductivity. Preferred metallic catalyst supports are comprised of copper. One problem which still remains is corrosion and degradation of the metallic catalyst support under certain chemical reactions.
For example, reactions involving oxidizing acids, such as nitric acid and sulfuric acid, and acids containing Fe(III), which come into contact with the copper catalyst supports cause the copper to dissolve. Copper is also subject to oxidation when it is contacted with solutions containing Fe(III), Hg(II), Sn(IV), Cu(II), and other ions that are readily susceptible of reduction, as well as ammonia ions or substituted ammonia ions. As another example, chloride, cyanide, and ammonia can form complexes with copper. Hydrogen chloride, hydrogen fluoride, as well as many halogenated hydrocarbons, can also react with copper to cause corrosion.
Contacting of a metallic support structure with corrosive agents in a thermal chemical reactor will result in the eventual destruction of the catalyst system, deterioration of production yields, and may require frequent replacement of the catalyst system, which could be prohibitively expensive. Additionally, exposure of highly conductive metallic supports to certain chemical reaction conditions can lead to undesired side-reactions because the metal support may have catalytic activity for by-product formation.
Accordingly, it would be desirable to provide a catalyst system having a metallic support that has a high intrinsic thermal conductivity, but which is not susceptible to corrosion and/or other deterioration due to contact with the chemical reactants, or that contributes to undesirable side reactions.